One of the main problems which farmers encounter in their fields is the exhaustion that the land suffers as a result of the practice of monculture or due to physical factors which cause erosion of the farmland. As a measure to prevent the exhaustion or wasting of such farmland, numerous techniques have been practiced, which range from the disposition or arrangement of the furrows to avoid erosion caused by wind, crop rotation, etc., to the use of fertilizers which supply the nutrients which the crops absorb, combined with the use of improved seeds, such as hybrids.
When farmers say that their land is "exhausted", they mean that the yield of their fields is too low and of poor quality. This is due mainly to the absence of organic matter, which has been consumed by the previous crops, that is, the depletion of vital nutrients such as phosphorus, magnesium, potassium and nitrogen compounds, causing a disequilibrium in the nutritional balance of the ground responsible for bearing new crops, this being detected by the reduction of the top soil or humus on the farmland.